Space by Paul Sutter 11/12/2022
As cosmic strings — exotic wrinkles in space-time left over from the earliest moments of the Big Bang — travel, they may trigger the formation of magnetic fields in their wakes, new research suggests. These magnetic fields would then soak the universe, thereby explaining the magnetization of galaxies and clusters, scientists propose in a new paper.
Almost every substantial object in the universe hosts a magnetic field. Smaller objects, like planets and stars, generate their own magnetic fields from dynamo actions inside them, where swirling flows of electrically charged plasma force weak magnetic fields to fold over themselves.
At larger scales, astronomers have observed magnetic fields inside nebulas, supernova remnants and protoplanetary disks. In those cases, complex flows of charged particles can generate weak fields.
Some of the largest objects in the universe, like galaxies and clusters of galaxies, also maintain magnetic fields. They're typically very weak — around a millionth the strength of Earth's magnetic field — but they are tremendous, in some cases stretching for millions of light-years.
Astronomers aren't exactly sure how galaxies and clusters get their magnetic fields. To make a magnetic field, you need charged particles moving together. But at the early stages of the universe's development, before the appearance of the first stars and galaxies, the cosmos was electrically neutral. A neutral gas can't generate magnetic fields on its own, so somehow, the universe had to create a magnetic field.
More:
https://www.space.com/big-bang-cosmic-strings-magnetic-fields
